The present invention relates generally to a hermetic compressor assembly and, more particularly, to such a compressor assembly having a compressor mechanism mounted within a hermetically sealed housing, wherein it is desired to limit the axial and lateral movement of the compressor mechanism relative to the housing, and to minimize the transmission of noise and vibration from the compressor mechanism to the housing.
In general, compressor assemblies of the type to which the present invention pertains comprise a motor-compressor unit mounted within a hermetically sealed housing. The motor-compressor unit includes an electric motor drivingly coupled to a positive displacement compressor mechanism for compressing refrigerant. During compressor operation, the steady-state inertial forces produced by the rotating masses of the unit are substantially balanced by the provision of counterweights in both the motor and the compressor mechanism, and by the location of mounting means at the axial center of mass. Furthermore, the axially supported mass of the motor-compressor unit helps dampen any axial vibratory forces. However, gas load forces produced by gas compression, and torque forces imparted to the compressor by the dynamic operation of the motor during starting and stopping, result in vibratory forces in a lateral plane.
Several prior art methods for immovably mounting a motor-compressor unit within a housing involve direct attachment therebetween, such as by circumferentially welding, clamping, or shrink fitting a mounting flange of the compressor mechanism to the housing sidewall. Alternatively, a mounting plate to which the compressor mechanism is attached may serve as the mounting flange. In one such arrangement, the housing comprises two interfitting portions between which the mounting flange or mounting plate is clamped or axially supported. Where the flange is only axially supported, the aforementioned lateral forces may cause rotation of the motor compressor unit within the housing.
A problem associated with prior art mounting mechanisms providing direct mechanical attachment between the compressor mechanism and the housing, is that vibrations are mechanically transmitted to the housing through the mounting mechanism, thereby producing noise and vibration in the housing. Also, other noises produced by the compressor mechanism can be transmitted directly to the housing through the mounting mechanism.
In order to reduce the transmission of vibration and noise from the compressor mechanism to the housing, there have been developed resilient suspension mounting systems incorporating springs and the like, which necessarily permit substantial movement of the compressor within the housing. As previously alluded to, it is desirable that the transmission of vibration and noise to the housing be minimized; however, it is also important, particularly in direct suction hermetic compressors wherein a suction tube extends between the housing sidewall and the compressor crankcase, that the compressor mechanism be limited in its movement relative to the housing so as to avoid damage to the compressor. Specifically, where the suction tube extends through a pressurized housing interior and includes O-ring seals at its connecting ends, damage to the O-ring seals could result from excessive movement of the compressor mechanism relative to the housing.
While the prior art mounting mechanisms have addressed separately the problems of restricting compressor movement relative to the housing and minimizing vibration and noise transmission from the compressor to the housing, a satisfactory combined solution has not been proposed, particularly for a direct suction hermetic compressor assembly exhibiting the aforementioned lateral vibratory forces. Instead, the prior art suspension mounting mechanisms have, for the most part, emphasized axially oriented spring support. Such systems inherently lack lateral support, which results in excessive lateral movement of the compressor mechanism and associated damages caused thereby.